Such pliers are also called crimping pliers or pressing pliers. Depending on the design of the work piece, especially in case of fittings, tubes and the like to be crimped, substantial pressing forces have to be applied onto the work piece. On the other hand, such work pieces may have comparatively great dimensions. Consequently, the crimping die being formed by two dies should have a great opening in the opened position of the pliers to be able to move the two dies over the work piece to be crimped in the opened position of the pliers. At the beginning of the closing movement of the pliers, there are no or no substantial pressing forces to be overcome. Contrarily, the pressing forces to be applied during the actual crimping movement of the work piece are substantial.
Pliers for crimping work pieces are known from German patent application DE 197 09 639 A1. The pliers include two handles being movable with respect to one another by one hand. To pivot jaws are supported by a joint. One of the pivot jaws is connected to a stationary handle to form a stationary portion of the pliers. The other pivot jaw is pivotally connected to the stationary portion of the pliers by the joint. The pliers include separated dies forming a crimping die. A locking mechanism serves to reach a defined end position of the separated dies. A pressure lever is arranged between the handles, and it is pivotable by the supporting joint. The pressure lever together with a section of the movable handle forms a toggle lever drive. The two dies and the corresponding pivot jaws are designed as one piece. They are produced by precision casting. The fixed connection of the combined pivot jaw/die to the stationary handle is disadvantageous. The preciseness of the finished crimped work piece highly depends on the realizable process tolerances with which the elements of the pliers are produced and which are used to assemble the pliers. Consequently, in many cases it is necessary to rework the pliers. The known pliers include handles made of molded plastic. These handles bring a great stability at a reduced exactness. Since the material flows, disadvantageous displacements of prearrange bores cannot be prevented.
Pliers for producing solderless connections between current conduits and corresponding connection elements by crimping the work pieces are known from German Auslegeschrift DE-AS 21 49 167. The pliers have a plate design, and they provide the corresponding advantages. The rather simple and exact production of the plates, for example by punching, is advantageous.
Linearly driven pliers having a plate design are known from German patent 34 11 397 C2. The necessary forces for producing solderless connections are not substantial.